Incomplete HCV Testing Common, CDC Says

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Initial screening for hepatitis C is with enzyme immunoassays which detect HCV antibodies. Confirmation of the presence or absence of infection is then performed with tests for HCV RNA which are also used to quantify the amount of HCV present at specific time points during therapy.

This report indicates that about half of persons newly reported with hepatitis C lack HCV RNA results, which are necessary to identify current infection.

Nearly half of Americans who test positive for hepatitis C (HCV) may not go on to get the second test necessary to confirm or refute the infection, according to the CDC.

In surveillance in two major cities and six states over a 7-year period, 49.2% of newly reported HCV patients had only the first test, for antibodies to the virus, the agency said online in a Vital Signs report in Morbidity and Mortality Weekly Report.

Without the second test, for HCV RNA, it remains unclear whether those positive antibody tests represent real evidence of infection, false-positives, or leftover antibodies from a cleared infection, the agency noted.

Complete testing is "critical" to ensure that patients get proper treatment, CDC Director Tom Frieden, MD, said in a telephone media briefing.

"Get tested to know if you have the infection now, because, if so, care and treatment really could save your life," Frieden said.

Although some people can clear the virus on their own, Frieden noted, about 80% do not, leaving them vulnerable -- without treatment -- to liver disease and cancer.

Knowing they are currently infected, Frieden said, allows patients to monitor their liver's condition, decide when or if to seek treatment, make lifestyle choices (such as avoiding alcohol and some medications) that might lead to further liver damage, and get vaccinated against hepatitis B.

Given the results of the surveillance data, combined with previous research suggesting that about 3 million Americans have HCV and up to 75% don't know it, the CDC also issued an updated guidance for clinicians and laboratory workers.

The major change from the last guidance, issued in 2003, is to suggest that all people who have an antibody-positive test should go on to the second, confirmatory test for HCV RNA.

Taken together, the two tests can identify people with current infection, the agency said.

The updated guidance comes at a time of ferment in HCV treatment.

The FDA has approved two drugs that attack the viral protease enzyme, telaprevir (Incivek) and boceprevir (Victrelis). When added to the former standard of care -- pegylated interferon and ribavirin -- both drugs markedly improved clearance rates.

A host of other so-called direct-acting agents are also in the pipeline and expected to enter the clinic soon. Many are able to act in combination without interferon, an immune-boosting medication that is regarded as difficult to tolerate and dangerous to use.

The data in the Vital Signs report comes from San Francisco and New York City, as well as New York State, Minnesota, Colorado, Oregon, Connecticut, and New Mexico and were collected from 2005 through 2011.

Not all sites contributed data for all years -- Connecticut didn't start reporting until 2009 -- and people who tested negative for HCV were not reported.

Nonetheless, the CDC reported, 217,755 people were newly reported with a positive HCV test, including 107,209 who had only the HCV antibody test and 110,546 who had both tests and were therefore currently infected.

Although most people with HCV have not been tested, the data suggest that "even among those individuals who have received that initial antibody test, as many as half do not know for sure that they still carry the virus," said John Ward, MD, director of the agency's Division of Viral Hepatitis.

Of those who have had only the antibody test, "it's likely that most of these individuals are still infected with hepatitis C but have not received that follow-up test necessary to confirm the infection and serve as a gateway to them receiving the care and appropriate treatment they need," Ward said.

The findings underscore the impact of HCV on the Baby Boomers -- 67% of all those with current infection (both tests positive) were among those born from 1945 through 1965.

Among the sites that reported deaths, 6,734 of 197,844 persons newly reported with HCV infection were known to have died; 71.5% of those deaths were among people born in the 1945-1965 period.

Baby Boomers "may not remember everything that happened in the '60s and '70s, but their liver does," Frieden said.

Minnesota had the lowest proportion of those who had only the first test, at 23%, while New Mexico had the highest, at 76%.

The report cautioned that the findings are from only eight sites and may not reflect what is happening in other cities and states.

Also, the agency said, only positive results were reported, so it's not clear how many of the people who were antibody-positive turned out to be RNA-negative.

The analysis was supported by the CDC. Authors are employees of the agency and of the New York City Department of Health and Mental Hygiene.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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